1. Field of the Invention
This invention relates to vegetable harvesting and more particularly to leaf topping vegetables, such as bulb onions.
2. Related Art
Typically bulb onions are harvested by uprooting them with a breaker bar that is pulled in the soil beneath the onions thereby surfacing the bulbs. In many cases the leafy tops of these uprooted onions are manually cut before the bulbs are removed from the field. In other situations, the untopped onions are first harvested and then manually topped at the packing area. However, the manual processes are slow, expensive, and prone to injuring workers.
As a consequence to the above problems, many inventors have addressed the general problem of harvesting vegetables and the more specific problem of leaf topping. Issued patents relevant to the extant invention are reviewed hereinafter. As early as 1908, Ellinwood (U.S. Pat. No. 894,262) disclosed equipment that lifts cabbages from the ground by grasping the cabbage head between two cooperating “sprocket chains” and moving the heads to a region where the root stumps are cut off by opposed and cooperating cutting disks. Although not a leaf topper, Ellinwood's invention set the basis for many of the improvements that followed.
Tateyama in (U.S. Pat. No. 2,625,781) teaches an onion harvesting machine that includes forwardly projecting fingers to lift the onion tops while the onions are still in the soil. The tops are then grasped between a pair of opposed and inclined wedge shaped belts. After the onion top is grasped the forward motion of the machine and the incline of the moving belts pull the onions from the soil. The belts then transport the onions past a pair of cutting blades (disks) to remove the tops.
Hood et al. (U.S. Pat. No. 4,629,005) invented a harvester for bulb, root and leafy vegetable products that includes cutting surfaces forced through the soil to uproot the product. The leafy tops are then grasped between a cooperating pair of moving belts to bring the product to an area where they are reoriented to a horizontal disposition. The inventors allow for the removal of the leafy tops by providing an optional cutter operating adjacent to the entrance of the product to the grasping belts. The cutter comprises a pair of cutter blades or, alternatively, a pair of overlapping cutting discs.
Ross et al. (U.S. Pat. No. 5,107,664) discloses a vegetable topper for cutting the leafy tops off of tubers, such as onions, as they lie in the field. Ross provides a vegetable topper that uses a vacuum to lift the tops for cutting. A linearly reciprocating sickle blade provides the cutting action. An assortment of conveying devices handle the movement of the bulbs both before and after the topping process.
U.S. Pat. No. 5,197,549 discloses an onion topper that may include a front-end gathering and lifting assembly, a transport assembly, and a horizontal cutting table provided by a moving chain conveyor. A fan beneath the cutting table may blow a stream of air upwardly through suitable ducting to raise the leaf tops of the onions where a reciprocating sickle-cutting member then removes them. The cut onion top may be blown out a discharge chute by the same stream of air and the onion bulbs exit at the back of the machine via a discharge assembly.
Matlock (U.S. Pat. No. 5,207,277) teaches a “bulb harvester” with structure for lifting the bulb foliage for presentation to the “crack” between a pair of upwardly inclined moving belts. With these belts the bulbs are moved rearward on the machine where the lifted foliage encounters a second and lower “crack” between a second pair of belts. The sharper incline of the first pair of belts with respect to the lower belt draws the bulb upward until the upper portion of the bulb rests against the bottom plane of the lower belt. Subsequently a set of interleaved cutting wheels operating just above the lower belt remove the bulb's foliage (leafy top).
Saito (U.S. Pat. No. 5,363,634), in a manner similar to Ross et al. provides a vegetable topper that uses a vacuum to lift the tops for cutting. A linearly reciprocating sickle blade provides the cutting action. An assortment of conveying devices handle the movement of the bulbs both before and after the topping process.
Abe (U.S. Pat. No. 5,431,231) discloses a harvester for root vegetables that is similar to other patents described above that incorporate inclined belt conveyors that grip the foliage for presentation to rotating cutter wheels.
Shuknecht (U.S. Pat. No. 5,750,171) teaches a plurality of longitudinal, parallel, generally horizontal, and spaced moving belts for moving bulbs through the apparatus. Adjacent belts operating at differing speeds cause the bulbs to rotate and gyrate randomly as they are being conveyed. The motion of the onions causes the bulbs to assume momentarily an attitude to permit the uncut stems to extend downwardly between the belts. Below and close to the belts is a rotating blade for cutting the momentarily depending bulb stems (tops or roots).
Helmbuch (U.S. Pat. No. 5,778,771) provides a vegetable topper that includes a plurality of spaced rollers which are mounted on a pair of laterally spaced roller chain loops such that the rollers are able to freely spin relative to the roller chains. The rollers define a bed on which vegetables flow along the bed generally perpendicular to the rotational axes of the rollers. As the vegetable (e.g. onions) move along the rollers, their tops tend to drop downwards between the spaced rollers wherein they encounter cutter blades. Helmbuch also provides rotating paddle wheels having a plurality of flexible paddle wheel fins disposed below the roller spaces. The rotating fins engage the onions to further promote the downward positioning of the tops for presentation to the cutting blades.
It is clear from the prior patent activity that harvesting vegetables, and bulb onions in particular, has been a vexing issue. Close study of the prior art shows evolutionary progress but clearly there is room for improvement in terms of simplicity, safety, productivity and versatility. Many of the existing harvesting machines integrate the process of extracting the onions from the soil along with the topping operation. This adds additional complexity to an already difficult process thus reducing reliability and overall productivity. Another problem with existing harvesters and leaf toppers is their relatively poor performance in damp soils and with wet leaf tops.
Also, in many geographical regions, for example, in the southern United States, onions are typically harvested when the aboveground portion of the plants are still quite succulent. This presents a particular problem in that topping apparatus can rapidly become fouled with sticky onion juice causing the machine to jam and also to often leave an undesirable stain or residue on succeeding bulbs.